102 DISCOPHOR^. Part III. 



like heavy leads sinking among the rest. This independence of motion among the 

 many tentacles of one and the same bunch, and among those of different bunches, 

 is truly remarkable in an animal in which no trace whatsoever of an independent 

 nervous system can be found. Nor is the mode in which they change their aspect, 

 when considered singly, less curious. A single tentacle may be shortened suddenly, 

 as if by a jerk, and rise among those which surround it, without producing the 

 slightest apparent disturbance, until it is shortened to its minimum; or many may 

 be seen playing in that way at the same time, in different bunches; but I have 

 never seen the majority of the tentacles of one bunch, or the larger portion of 

 several bunches, suddenly contracting at the same time, even when irritated, 

 though, under such circumstances, a great many tentacles may contract together. 

 The manner in which they elongate is equally varied; at times they stretch grad- 

 nally, and, apparently, uniformly along their whole length, while at other times, and 

 this is seen particularly in tentacles which have been shortened into a club-shaped 

 attitude, the thicker extremity seems to drop, as if it were falling off from the 

 thin thread to which it is attached, when a marked elongation of the thinner part 

 takes place, and the club pauses again for some time immovably suspended at the 

 same height; then another and another fall brings it lower and lower, until it is 

 uniformly stretched for its whole length. At other times, again, they may be seen 

 alternately contracting and expanding in rather quick succession, as if undecided 

 whether to elongate or to shorten; when, by a sudden jerk, they may be entirely 

 withdrawn or fall to their full length. A closer examination of the thickest 

 tentacles in PI. III., will bring to view zigzag or spiral lines in their interior, or 

 a seeming difference in the transparency between different points of their thick- 

 ness. This is owing to the circumstance that all these tentacles are hollow, and 

 that their cavity assumes different shapes, in different stages and in different modes 

 of contraction. When the tentacles are at rest, in their contracted state, their 

 extremity is generally club-shaped, and the cavity assumes the appearance of an 

 elongated bead in their interior; but while shortening rapidly and unequally, the 

 cavity becomes undulating, and presents the appearance of zigzags or of a spiral, 

 as is best seen in magnified views, PL V. Figs. 4, 7, 8, and 9. The internal 

 structure of the tentacles fully explains this inequality; for, though tubular, there 

 is in all tentacles, on one side of the tube, between the outer layer of cells which 

 form its surface and among which are imbedded the clusters of lasso-cells, as may 

 be particularly well seen in PI. V. Figs. 5 and 6, a band of contractile fibres, which 

 runs for the whole length of the tentacle (PL V. Figs. 4, 7, 8, 9, and 10 b), and 

 by its contraction must necessarily produce inequalities in the shortening of differ- 

 ent sides of the tentacle, as well as undulations in its cavity. These fibres, how- 

 ever, are themselves very elongated cells. 



